I know this is an old post but I hope it reaches the original poster.
I am currently reaching this family. W V Custer and Sarah Parker or Parhan. I concluded this is in fact the same person in Vernon County.
Their daughter Sarah Frances Custer b 1861 Moniteau County, Missouri is living with the Small family in 1870 in Lebanon, Cooper, Missouri. Probably because her mother either died or divorced W V Custer. Also she has a sister 13 yr old Mattie Custer living with her and her husband in 1880. I am hoping someone out there can shed some light on this family for me or point me in the right direction with the mysteries described here.